Impulse response measuring device of combined high-frequency current sensor

Abstract

The invention discloses an impulse response measuring device of a combined high-frequency current sensor. A large number of noise signals often exist in a field high-voltage cable partial discharge test, the noise signals mainly comprise random white noise, random pulse noise, periodic pulse noise and the like, and the partial discharge belongs to the random pulse signals with small energy. On-site noise interference can cause great influence on detection of partial discharge of a high-voltage cable, and even noise signals are misjudged as partial discharge signals or annihilation partial discharge signals in severe cases, so that detection misjudgment or missing detection is caused. In order to identify noise signals in high-voltage cable partial discharge measurement, the impulse response of the combined high-frequency current sensor needs to be measured and obtained. Therefore, it is necessary to provide an impulse response measuring device for the combined high-frequency current sensor to obtain the impulse response of the combined high-frequency current sensor, a technical basis is provided for realizing a cable partial discharge noise identification technology based on the combined high-frequency current sensor, and the impulse response measuring device has important engineering practical value.

Description

Technical Field

[0001] The invention relates to the field of insulation state detection of high-voltage cable lines, and in particular to an impulse response measuring device of a combined high-frequency current sensor. Background Art

[0002] Compared with overhead lines, underground cables have the advantages of higher reliability and safety, small footprint and strong transmission capacity. Therefore, with the development of urban power distribution networks in my country, the underground cabling of overhead lines has become one of the important contents of urban power grid construction. Due to the good electrical and mechanical properties of cross-linked polyethylene cables, the main power cables produced and operated in my country are XLPE cables, followed by a small amount of oil-filled cables. As of December 2023, the State Grid has 23,888 high-voltage cables of 66 kV and above, with a total loop length of 46,519.3 kilometers, including 577.2 kilometers of submarine cables. However, due to the complexity of the XLPE cable laying environment and the influence of external factors, power outages and fire accidents caused by cable insulation failures still occur from time to time, causing certain economic losses. There are many reasons for cable failures. External force damage is the main cause of cable failures, followed by cable body / insulation aging and accessory defects / installation process. The defects in the cable body are mainly caused by imperfect production technology, which results in bubbles or impurities in the cable insulation; the defects in the intermediate joints are mainly caused by the complexity of the laying environment during on-site construction and the differences in the process level of operators. These local defects will lead to local field concentration and partial discharge.

[0003] Partial discharge is the main manifestation of latent defects in high-voltage cable lines. It is not only the main cause of insulation aging, but also the main characteristic parameter reflecting the insulation state. The factory test of the high-voltage cable body needs to be tested for partial discharge. On the other hand, the handover test after the high-voltage cable is laid also needs to be tested for variable frequency resonance synchronous partial discharge. These tests can accurately discover the partial discharge phenomenon in the high-voltage cable line and are an intuitive, ideal and effective test method for diagnosing the quality of high-voltage cable line products. However, there are often a large number of noise signals during the on-site partial discharge test of high-voltage cables. The noise signals mainly include random white noise, random pulse noise, periodic pulse noise and other types. Since the partial discharge itself is a random pulse signal with low energy, the on-site noise interference will have a great impact on the detection of partial discharge of high-voltage cables. In severe cases, the noise signal may even be misjudged as a partial discharge signal or annihilate the partial discharge signal, resulting in misjudgment or missed detection. In order to identify the noise signal in the partial discharge measurement of high-voltage cables, it is necessary to measure the impulse response of the combined high-frequency current sensor. Therefore, it is necessary to propose an impulse response measurement device for a combined high-frequency current sensor to obtain the impulse response of the combined high-frequency current sensor, which provides a technical basis for realizing cable partial discharge noise identification technology based on the combined high-frequency current sensor and has important engineering practical value. Summary of the invention

[0004] The present invention provides an impulse response measuring device for a combined high-frequency current sensor, which can solve the measurement problem of obtaining the impulse response of the combined high-frequency current sensor. The impulse response measuring device for the combined high-frequency current sensor is composed of a pulse generator, a radio frequency current probe calibration device and a digital oscilloscope.

[0005] The technical solution of the present invention is achieved in this way:

[0006] The invention discloses an impulse response measuring device for a combined high-frequency current sensor, comprising a pulse generator, a radio frequency current probe calibration device, a digital oscilloscope, a low-frequency band high-frequency current sensor and a high-frequency band high-frequency current sensor; the output of the pulse generator is connected to the input of the radio frequency current probe calibration device, and the output is a pulse voltage signal; the output of the radio frequency current probe calibration device is connected to a non-inductive resistor; the output of the low-frequency band high-frequency current sensor is connected to the input of a digital oscilloscope channel 1; the output of the high-frequency band high-frequency current sensor is connected to the input of the digital oscilloscope channel 1; the input of the digital oscilloscope channel 1 is respectively connected to the outputs of the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor.

[0007] The pulse generator output is connected to the input of the RF current probe calibration device. The output is a pulse voltage signal with a rise time of no more than 350ps, a fall time of no less than 100ns, an amplitude of no less than 50V, an output impedance of 50 ohms, and a repetition frequency of no less than 50Hz.

[0008] The input of the RF current probe calibration device is connected to the output of the pulse generator, and the output is connected to a 50 ohm non-inductive resistor and a 20mm diameter center conductor.

[0009] The power of a 50 ohm non-inductive resistor is not less than 2W, its frequency range is DC to 1000MHz, and its standing wave ratio is not higher than 1.5.

[0010] The output of the low-frequency high-frequency current sensor is connected to the input of channel 1 of the digital oscilloscope. The low-frequency cutoff frequency is 100kHz, the high-frequency cutoff frequency is 3MHz, the transmission impedance is not less than 10mV / mA, and the output impedance is 50 ohms.

[0011] The inner diameter of the low-frequency band high-frequency current sensor shall not be less than 35mm and the outer diameter shall not be greater than 80mm.

[0012] The high-frequency current sensor output in the high-frequency band is connected to the input of channel 1 of the digital oscilloscope 15. Its low-frequency cutoff frequency is 3MHz, its high-frequency cutoff frequency is 100MHz, the transmission impedance is not less than 5mV / mA, and the output impedance is 50 ohms.

[0013] The inner diameter of the high-frequency current sensor in the high-frequency band shall not be less than 35mm and the outer diameter shall not be greater than 80mm.

[0014] The digital oscilloscope channel 1 input is connected to the outputs of the low-band high-frequency current sensor and the high-band high-frequency current sensor in sequence, the analog bandwidth is not less than 1 GHz, the sampling rate is not less than 5 GHz, the number of channels is not less than 2 channels, the record length is not less than 1M, and it has data storage function.

[0015] After adopting the above design, the present invention has at least the following advantages:

[0016] The invention discloses an impulse response measuring device for a combined high-frequency current sensor, which realizes the measurement of the impulse response of the combined high-frequency current sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a device for measuring impulse response of a combined high-frequency current sensor;

[0018] exist Figure 1 Among them, 11 is a pulse generator, 12 is a radio frequency current probe calibration device, 15 is a digital oscilloscope, 13 is a low frequency band high frequency current sensor, and 14 is a high frequency band high frequency current sensor. DETAILED DESCRIPTION

[0019] Reference Figure 1As shown, the combined high-frequency current sensor is composed of a low-frequency band high-frequency current sensor and a high-frequency band high-frequency current sensor. Measuring the impulse response of the combined high-frequency current sensor is to measure the impulse response of the low-frequency band high-frequency current sensor and the impulse response of the high-frequency band high-frequency current sensor respectively. According to the principle of impulse response, the ideal unit impulse signal cannot be generated by a physical device. On the other hand, the high-frequency cutoff frequency of the low-frequency band high-frequency current sensor is 3MHz, and the high-frequency cutoff frequency of the high-frequency band high-frequency current sensor is 100MHz. Therefore, a pulse signal with a bandwidth of not less than 350MHz can be used to simulate the unit impulse signal, thereby obtaining the impulse response of the combined high-frequency current sensor.

[0020] According to the above principles, the performance parameters of the pulse generator of the impulse response measurement device of the combined high-frequency current sensor need to meet the requirements that the output is a pulse voltage signal, the rise time is not more than 350ps, the fall time is not less than 100ns, the amplitude is not less than 50V, the output impedance is 50 ohms, and the repetition frequency is not less than 50Hz; the performance parameters of its radio frequency current probe calibration device need to meet the requirements that the output is connected to a 50-ohm non-inductive resistor, the input has a 50-ohm characteristic impedance, a 20mm diameter center conductor, the 50-ohm non-inductive resistor power is not less than 2W, the frequency range is DC to 1000MHz, and the standing wave ratio is not higher than 1.5; the performance parameters of its digital oscilloscope need to meet the requirements that the analog bandwidth is not less than 1GHz, the sampling rate is not less than 5GHz, the number of channels is not less than 2 channels, the record length is not less than 1M, and it has data storage function.

[0021] The present invention provides an impulse response measuring device for a combined high-frequency current sensor. The steps of using the device to measure the impulse response of the combined high-frequency current sensor can be divided into the following 11 steps:

[0022] 1. Pass the low-frequency high-frequency current sensor 13 through the central conductor of the radio frequency current probe calibration device 12, that is, correctly install the low-frequency high-frequency current sensor 13 in the radio frequency current probe calibration device 12;

[0023] 2. Connect the output of the pulse generator 11 to the input of the RF current probe calibration device 12;

[0024] 3. Connect the output of the low-frequency high-frequency current sensor 13 to the input of channel 1 of the digital oscilloscope 15;

[0025] 4. Turn on the pulse generator 11 output;

[0026] 5. Save the impulse response data of the low-frequency band high-frequency current sensor of the digital oscilloscope 15 channel 1;

[0027] 6. Turn off the output of the pulse generator 11, take out the low-frequency band high-frequency current sensor 13 from the radio frequency current probe calibration device 12, and disconnect the output of the low-frequency band high-frequency current sensor 13 from the input of channel 1 of the digital oscilloscope 15;

[0028] 7. Pass the high-frequency band high-frequency current sensor 14 through the central conductor of the radio frequency current probe calibration device 12, that is, correctly install the high-frequency band high-frequency current sensor 14 in the radio frequency current probe calibration device 12;

[0029] 8. Connect the output of the high-frequency current sensor 14 in the high-frequency band to the input of channel 1 of the digital oscilloscope 15;

[0030] 9. Turn on the pulse generator 11 output;

[0031] 10. Save the impulse response data of the high-frequency current sensor in the high-frequency band of the digital oscilloscope 15 channel 1;

[0032] 11. Turn off the output of the pulse generator 11, take out the high-frequency band high-frequency current sensor 14 from the radio frequency current probe calibration device 12, and disconnect the output of the high-frequency band high-frequency current sensor 14 and the input of channel 1 of the digital oscilloscope 15.

[0033] It can be seen that the impulse response measurement device of the combined high-frequency current sensor of the present invention realizes the impulse response measurement of the combined high-frequency current sensor by injecting an analog impulse signal into the combined high-frequency current sensor, and has important engineering practical value.

Claims

1. An impulse response measuring device for a combined high-frequency current sensor, characterized in that: It includes a pulse generator, a radio frequency current probe calibration device and a digital oscilloscope; the output of the pulse generator is connected to the input of the radio frequency current probe calibration device, the output is a pulse voltage signal, the output of the radio frequency current probe calibration device is connected to a non-inductive resistor, the output of a low-frequency band high-frequency current sensor is connected to the input of digital oscilloscope channel 1, the output of a high-frequency band high-frequency current sensor is connected to the input of digital oscilloscope channel 1, and the input of digital oscilloscope channel 1 is connected to the outputs of the low-frequency band high-frequency current sensor and the high-frequency band high-frequency current sensor in sequence.

2. The impulse response measuring device of the combined high-frequency current sensor according to claim 1, characterized in that: The pulse generator output is connected to the input of the RF current probe calibration device. The output is a pulse voltage signal with a rise time of no more than 350ps, a fall time of no less than 100ns, an amplitude of no less than 50V, an output impedance of 50 ohms, and a repetition frequency of no less than 50Hz.

3. The impulse response measuring device of the combined high-frequency current sensor according to claim 1, characterized in that: The input of the RF current probe calibration device is connected to the output of the pulse generator, and the output is connected to a 50 ohm non-inductive resistor and a 20mm diameter center conductor.

4. The impulse response measuring device of the combined high-frequency current sensor according to claim 3, characterized in that: The power of a 50 ohm non-inductive resistor is not less than 2W, its frequency range is DC to 1000MHz, and its standing wave ratio is not higher than 1.

5.

5. The impulse response measuring device of the combined high-frequency current sensor according to claim 1, characterized in that: The output of the low-frequency high-frequency current sensor is connected to the input of channel 1 of the digital oscilloscope. The low-frequency cutoff frequency is 100kHz, the high-frequency cutoff frequency is 3MHz, the transmission impedance is not less than 10mV / mA, and the output impedance is 50 ohms.

6. The impulse response measuring device of the combined high-frequency current sensor according to claim 5, characterized in that: The inner diameter of the low-frequency band high-frequency current sensor shall not be less than 35mm and the outer diameter shall not be greater than 80mm.

7. The impulse response measuring device of the combined high-frequency current sensor according to claim 1, characterized in that: The high-frequency current sensor output in the high-frequency band is connected to the input of channel 1 of the digital oscilloscope. Its low-frequency cutoff frequency is 3MHz, its high-frequency cutoff frequency is 100MHz, the transmission impedance is not less than 5mV / mA, and the output impedance is 50 ohms.

8. The impulse response measuring device of the combined high-frequency current sensor according to claim 7, characterized in that: The inner diameter of the high-frequency current sensor in the high-frequency band shall not be less than 35mm and the outer diameter shall not be greater than 80mm.

9. The impulse response measuring device of the combined high-frequency current sensor according to claim 1, characterized in that: The digital oscilloscope channel 1 input is connected to the outputs of the low-band high-frequency current sensor and the high-band high-frequency current sensor in sequence, the analog bandwidth is not less than 1 GHz, the sampling rate is not less than 5 GHz, the number of channels is not less than 2 channels, the record length is not less than 1M, and it has data storage function.

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